I'm troubleshooting an issue with a The Shadow I acquired a while back and have been working on. When firing either or both of the flippers, either via the buttons or in test mode, the game instantly resets. While this falls into the category of a WPC reset and is probably watchdog circuit-related, I'm not convinced that it's due to the typical culprits affecting the 5v or 12v supply. This is very much something that happens only when the flippers fire, and not seemingly randomly or otherwise. The game has sat on for about a half hour or more at a time in test and attract mode while I've been servicing it and I've yet to see a reset in either mode, unless/until the flippers fire.
I should also note that the flipper EOS switches (all of them) throw errors on boot. They are normally open in test and register properly when manually closed.
Things I've done so far (all measurements coming from my true RMS Fluke 8060a), using the Pinwiki WPC reset troubleshooting list (https://pinwiki.com/wiki/index.php?title=Williams_WPC#Game_resets) as a guide:
- Reseated all connectors, including J101, J114 and J210, many times
- Verified that line voltage is 122VAC and that matches what I'm getting with the game on and off at the internal supply
- Verified driver board (and all boards) are screwed in fully and grounded
- Flowed more solder to all of the flipper coil lugs, ensuring the diode leads are fully in contact
- Unplugged/plugged back in the 15-pin Molex at the transformer that carries 9VAC
- Checked pins at J101 and I don't see significant tarnish
- Measured VDC at TP2 and again at pin 32 of the game ROM and here I am seeing a bit of a drop - 4.925v at TP2 and 4.686v at pin32 of the ROM.
^-- Is this a clue of the root cause? Are these voltages too low on both sides? --^
- Tested BR2 on the Driver Board and while load using the method here (http://techniek.flipperwinkel.nl/wpc/index2.htm#reset) and got 9.6v. I also tested under load using this method (https://pinwiki.com/wiki/index.php?title=Williams_WPC#Using_a_Multimeter_to_Test_the_Bridge_Rectifier_and_Capacitors) and got 9.8-10.02v. Checking the capacitor I measured 183mVAC, which also seems to be a bit low but in range.
- Tested BR1 under load on the Fliptronics II board using method from flipperwinkel and got 67.5v-68.1v
- Went to test C2 on the Fliptronics board and HOLD UP - it's not there! It looks like it never was?! But I'm assuming this is factory normal on this game, from the pics I've seen.
Here are my thoughts on how I might troubleshoot further:
- Remove the flipper assemblies (which I just rebuilt and replaced ) and check all of the flipper diodes one by one by taking them momentarily out of circuit. They appear to be visibly wired properly, but I stupidly didn't test them when I had the assemblies out.
^--See attached photos. I verified wiring at the lugs matches the schematics and I believe the EOS switches can be wired either way and work fine. But please feel free to fact check me here.
- Check for a short on the flipper circuits. What's the best way to do this?
- Check thermistor: I don't think this would be the cause given how these resets are isolated only to the flippers engaging. But could it be?
Any additional suggestions or thoughts would be much appreciated. I've spent a number hours already on this and would love some guidance before I invest more time here. I'd like to be 100% sure this is a Power Driver or Fliptronics board issue and not something else before I engage a trusted professional here.
Many thanks in advance!